Inactivation of viruses in labile blood derivatives

ABSTRACT

There is disclosed a process for obtaining a protein-containing composition which is substantially free of lipid-containing viruses without incurring substantial protein denaturation comprising contacting said protein-containing composition with an effective amount of oleic acid, its ester or alkali or alkaline earth metal salt for a sufficient period of time to inactivate virus contained therein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to undenatured virus-free biologically active protein-containing compositions. More especially, this invention relates to the inactivation of viruses, especially lipid coated viruses, e.g., hepatitis B in human blood, blood component, blood plasma or any fraction, concentrate or derivative thereof containing blood proteins or non-blood sources including normal or cancer cells, the exudate from cancer or normal cells grown in culture, hybridomas, in products from gene splicing (DNA), etc., by the use of oleic acid, its esters and salts to the resultant products. In particular, this invention relates to blood plasma or other plasma protein-containing compositions which are to be rendered substantially free of hepatitis B and/or non-A and non-B hepatitis or other viral infectivity, such blood plasma or fractions thereof having valuable labile proteins, such as, for example, factor VIII.

2. Discussion of Prior Art

Numerous attempts have been made to inactivate viruses such as hepatitis B virus (HBV) in mammalian, especially human, blood plasma. It is the practice in some countries to effect inactivation of the hepatitis B virus in the blood plasma by contacting the plasma with a viral inactivating agent of the type which crosslinks with the proteinaceous portion of hepatitis B virus, or which interacts with the nucleic acid of the virus. For instance, it is known to attempt to inactivate hepatitis B virus by contact with an aldehyde such as formaldehyde whereby crosslinking to the protein is effected and the hepatitis B virus is inactivated. It is also known to effect inactivation of the virus by contact with beta-propiolactone (BPL), an agent which acts on the nucleic acid of the virus. It is further known to use ultraviolet (UV) light, especially after a beta-propiolactone treatment.

Other inactivating agents include lower alkyl esters of acetic acid for inactivation of flu virus (U.S. Pat. No. 3,655,871); glutaraldehyde (U.S. Pat. No. 3,983,229 and U.S. Pat. No. 4,070,454); tri-n-butyl-phosphate for inactivation of flu virus (U.S. Pat. No. 3,962,421); butylatedhydroxytoluene (U.S. Pat. No. 4,350,707); sulfhydryl (U.S. Pat. No. 3,651,211); ethyleneimine (U.S. Pat. No. 3,636,196 and U.S. Pat. No. 4,036,952); betapropiolactone combined with acetylethylenimine (U.S. Pat. No. 4,083,958) and tannin (U.S. Pat. No. 4,178,126). Detergents have also been disclosed as viral inactivating agents. See U.S. Pat. Nos. 4,314,997 and 4,315,919. Microwave has also been proposed and disclosed in U.S. Pat. No. 3,660,234. U.S. Pat. No. 4,424,206 discloses the use of heat. Various chlorinated hydrocarbons such as tetrachloroethylene have been proposed for the inactivation of myxoviruses (see U.S. Pat. No. 3,847,737).

Unfortunately, viral inactivity agents often alter, denature or destroy valuable protein components especially so-called "labile" blood coagulation factors of the plasma under conditions required for effective inactivation of virus infectivity. For instance, in such, factor VIII is inactivated or denatured to the extent of 50-90% or more of the factor VIII present in the untreated plasma. Because of the denaturing effects of these virus inactivating agents, it is necessary in the preparation of derivatives for administration to patients to concentrate large quantities of plasma so that the material to be administered to the patient once again has a sufficient concentration of the undenatured protein for effective therapeutic treatment. This concentration, however, does not affect reduction of the amount of denatured protein. As a result, the patient not only receives the undenatured protein but a quantity of denatured protein often many times that of the undenatured protein.

For instance, in the inactivation of hepatitis B virus in human blood plasma by beta-propiolactone, there is obtained as a result thereof, a plasma whose factor VIII has been 75% inactivated. The remaining 25% of the factor VIII is, therefore, present in such a small concentration, as a function of the plasma itself, that it is necessary to concentrate large quantities of the factor VIII to provide sufficient concentration to be of therapeutic value. Since such separation techniques do not efficiently remove denatured factor VIII from undenatured factor VIII, the material administered to the patient may contain more denatured protein than undenatured protein. Obviously, such inactivation is valuable from a standpoint of diminishing the risk of hepatitis virus infection. However, it requires the processing of large quantities of plasma and represents significant loss of valuable protein components. Furthermore, administration of large amounts of denatured proteins may render these antigenic to the host and thus give rise to autoimmune diseases, or perhaps, rheumatoid arthritis.

The loss of these valuable protein components is not limited to factor VIII, one of the most labile of the valuable proteins in mammalian blood plasma. Similar protein denaturation is experienced in respect of the following other valuable plasma components: coagulation factors II, VII, IX, X; plasmin, fibrinogen (factor I) IgM, hemoglobin, interferon, etc.

Factor VIII, however, is denatured to a larger extent than many of the other valuable proteins present in blood plasma.

As a result of the foregoing, except in the processing of serum albumin, a stable plasma protein solution which can withstand pasteurization, it is largely the practice in the United States in respect of the processing of blood proteins to take no step in respect of the sterilization for inactivation of viruses. As a result, recipients of factor VIII, gamma-globulin, factor IX, fibrinogen, etc., must accept the risk that the valuable protein components being administered may be contaminated with hepatitis viruses as well as other infectious viruses. As a result, these recipients face the danger of becoming infected by these viruses and having to endure the damage which the virus causes to the liver and other organ systems and consequent incapacitation and illness, which may lead to death.

The BPL/UV inactivation procedure discussed above has not so far been adopted in the United States for numerous reasons, one of which lies in the fact that many researchers believe that BPL is itself deleterious since it cannot be removed completely following the inactivation and thus may remain in plasma and plasma derivatives. BPL has been shown to be carcinogenic in animals and is dangerous even to personnel handling it.

Other methods for the inactivation of hepatitis B virus in plasma are known, but are usually impractical. One method involves the addition of antibodies to the plasma whereby an immune complex is formed. The expense of antibody formation and purification add significantly to the cost of the plasma production; furthermore, there is no assurance that a sufficient quantity of hepatitis B or non-A, non-B virus is inactivated. There is currently no test for non-A, non-B antibodies (although there is a test for the virus); hence, it is not possible to select plasma containing high titers of anti non-A, non-B antibody.

It is to be understood that the problems of inactivation of the viruses in plasma are distinct from the problems of inactivation of the viruses themselves due to the copresence of the desirable proteinaceous components of the plasma. Thus, while it is known how to inactivate the hepatitis B virus, by using crosslinking agents, for example, glutaraldehyde, nucleic acid reacting chemicals, for example BPL or formaldehyde, or oxidizing agents, for example chlorox, etc., it has been believed that these methods are not suitable for the inactivation of the virus in plasma due to the observation that most of these inactivating agents (sodium hypochlorite, formaldehyde, beta-propiolactone) denatured the valuable proteinaceous components of the plasma.

U.S. Pat. No. 4,315,919 to Shanbrom describes a method of depyrogenating a proteinaceous biological or pharmaceutical product by contacting such proteinaceous product with a non-denaturing amphiphile.

U.S. Pat. No. 4,314,997 to Shanbrom describes a method of reducing pyrogenicity, hepatitis infectivity and clotting activation of a plasma protein product by contacting the product with a non-denatured amphiphile.

Both Shanbrom '919 and '997 contemplate the use of a non-ionic detergent, for example, "Tween 80" as the amphilphile. It is shown in Ser. No. 514,375, assigned to the assignee hereof, with "Tween 80" by itself is relatively ineffective as a viral inactivating agent.

U.S. Pat. No. 3,962,421 describes a method for the disruption of infectious lipid-containing viruses for preparing sub-unit vaccines by contacting the virus in an aqueous medium with a wetting agent and a trialkylphosphate. Such aqueous medium is defined as allantonic fluid, tissue culture fluid, aqueous extract or a suspension of central nervous system tissue, blood cell eluate and an aqueous extract or suspension of fowl embryo. The patent does not describe hepatitis, nor is it concerned with preparation of blood derivatives containing labile blood protein substantially free of viral infectivity. It is concerned only with disrupting the envelope of lipid-containing viruses for the production of vaccines and not with avoiding or reducing protein denaturation en route to a blood derivative.

Problems may also exist in deriving valuable proteins from non-blood sources. These sources include, but are not limited to, mammalian milk, ascitic fluid, saliva, placenta extracts, tissue culture cell lines and their extracts including transformed cells, and products of fermentation. For instance, the human lymphoblastoid cells have been isolated an used to produce alpha interferon. However, the cell line in commercial use today contains Epstein-Barr virus genes. It has been a major concern that the use of interferon produced by these cells would transmit viral infection or induce viral caused cancerous growth.

The present invention is directed to achieving three goals, namely, (1) a safe, (2) viral inactivated protein-containing composition, (3) without incurring substantial protein denaturation. As shown above, these three goals are not necessarily compatible since, for example, beta-propiolactone inactivates viral infectivity, but is unsafe and substances such as formaldehyde inactivate viruses, but also substantially denaturate the valuable plasma proteins, for example, factor VIII.

It, therefore, became desirable to provide a process for obtaining protein-containing compositions which does not substantially denature the valuable protein components therein and which does not entail the use of a proven carcinogenic agent. More especially, it is desirable to provide blood protein-containing compositions in which substantially all of the hepatitis viruses and other viruses present are inactivated and in which denatured protein such as factor VIII account for only a small amount of the total amount of these proteins in the blood protein-containing composition.

It is a further object to provide products from cancer or normal cells or from fermentation processes following gene insertion which are substantially free of virus, especially lipid-containing viruses.

SUMMARY OF THE INVENTION

It has now been discovered, quite surprisingly, that while most of the viral inactivating agents denature factor VIII and other valuable blood plasma proteins, that not all viral inactivating agents have such effect. It has been discovered that a protein-containing composition such as blood proteins including whole blood, blood cell proteins, blood plasma, a blood plasma fractionation precipitate, a blood plasma fractionation supernatant, cryoprecipitate, cryosupernatant, or portion or derivative thereof or serum or a non-blood product produced from normal or cancerous cells (e.g. via recombinant DNA technology) is contacted for a sufficient period of time with oleic acid, its ester or salt that lipid-containing viruses such as the hepatitis viruses present in the composition are virtually entirely inactivated without substantial denaturation of proteins therein. By contacting a blood protein mixture or concentrate thereof or fraction thereof with oleic acid or a C₁₋₄ alkyl ester thereof or an alkali or alkaline earth metal salt thereof, hepatitis viruses can be substantially inactivated, e.g., to an inactivation of greater than 4 logs, while realizing a yield of protein activity to total protein of at least 60%.

By such procedures there is provided a blood protein-containing composition such as mammalian whole blood, blood cell derivative (e.g., hemoglobin, alpha-interferon, T-cell growth factor, platelet-derived growth factor, etc.), plasminogen activator, blood plasma, blood plasma fraction, blood plasma precipitate (e.g., cryoprecipitate, ethanol supernatant or polyethylene glycol supernatant), characterized by the presence of one or more blood proteins such as labile blood factor VIII having a total yield or protein activity to total protein of at least 60%, preferably at least 70%, said blood protein-containing composition having greatly reduced or virtually no hepatitis viruses. Virus in a serum is determined by infectivity titrations.

By the inactivation procedure of the invention, most if not virtually all of the hepatitis viruses contained therein are inactivated. The method for determining infectivity levels by in vivo chimpanzees is discussed by Prince, A. M., Stephen, W., Brotman, B. and van den Ende, M. C., "Evaluation of the Effect of Beta-propiolactone/Ultraviolet Irradiation (BPL/UV) Treatment of Source Plasma on Hepatitis Transmission by factor IX Complex in Chimpanzees, Thrombosis and Haemostasis", 44: 138-142, 1980.

The hepatitis virus is inactivated by treatment with oleic acid, its ester or salt described herein, and is not inactivated because of inclusion in the plasma of antibodies which bind with the hepatitis viruses and form immune complexes.

Inactivation of virus is obtained to the extent of at least "4 logs", i.e., virus in a serum is totally inactivated to the extent determined by infectivity studies where that virus is present in the untreated serum in such a concentration that even after dilution to 10⁴, viral activity can be measured.

DETAILED DESCRIPTION OF THE INVENTION

Blood is made up of solids (cells, i.e., erythrocytes, leucocytes, and thrombocytes) and liquid (plasma). The cells contain potentially valuable substances such as hemoglobin, and they can be induced to make other potentially valuable substances such as interferons, growth factors, and other biological response modifiers. The plasma is composed mainly of water, salts, lipids and proteins. The proteins are divided into groups called fibrinogens, serum globulins and serum albumins. Typical antibodies (immune globulins) found in human blood plasma include those directed against infectious hepatitis, influenza H, etc.

Blood transfusions are used to treat anemia resulting from disease or hemorrhage, shock resulting from loss of plasma proteins or loss of circulating volume, diseases where an adequate level of plasma protein is not maintained, for example, hemophilia, and to bestow passive immunization.

Whole blood must be carefully typed and cross matched prior to administration. Plasma, however, does not require prior testing. For certain applications, only a proper fraction of the plasma is required, such as factor VIII for treatment of hemophilia or von Willebrand's disease.

With certain diseases one or several of the components of blood may be lacking. Thus the administration of the proper fraction will suffice, and the other components will not be "wasted" on the patient; the other fractions can be used for another patient. The separation of blood into components and their subsequent fractionation allows the proteins to be concentrated, thus permitting concentrates to be treated. Of great importance, too, is the fact that the plasma fractions can be stored for much longer periods than whole blood and they can be distributed in the liquid, the frozen, or the dried state. Finally, it allows salvaging from blood banks the plasma portions of outdated whole blood that are unsafe for administration as whole blood.

Proteins found in human plasma include prealbumin, retinol-binding protein, albumin, alpha-globulins, beta-globulins, gamma-globulins (immune serum globulins), the coagulation proteins (antithrombin III, prothrombin, plasminogen, antihemophilic factor, factor IX, fibrin-stabilizing factor-factor XIII, fibrinogen), immunoglobins (immunoglobulins G, A, M, D, and E), and the complement components. There are currently more than 100 plasma proteins that have been described. A comprehensive listing can be found in "The Plasma Proteins", ed. Putnam, F. W., Academic Press, New York (1975).

Proteins found in the blood cell fraction include hemoglobin, fibronectin, fibrinogen, enzymes of carbohydrate and protein metabolism and products of blood cells, e.g., elastase, etc. In addition, the synthesis of other proteins can be induced, such as interferons and growth factors.

A comprehensive list of inducible leukocyte proteins can be found in Stanley Cohen, Edgar Pick, J. J. Oppenheim, "Biology of the Lymphokines", Academic Press, N.Y. (1979).

Blood plasma fractionation generally involves the use of organic solvents such as ethanol, ether and polyethylene glycol at low temperatures and at controlled pH values to effect precipitation of a particular fraction containing one or more plasma proteins. The resultant supernatant can itself then be precipitated and so on until the desired degree of fractionation is attained. More recently, separations are based on chromatographic processes. An excellent survey of blood fractionation appears in Kirk-Othmer's Encylopedia of Chemical Technology, Third Edition, Interscience Publishers, Volume 4, pages 25 to 62, the entire contents of which are incorporated by reference herein.

The major components of a cold ethanol fractionation are as follows:

    ______________________________________                                         Fraction  Proteins                                                             ______________________________________                                         I         fibrinogen, cold insoluble globulin; factor                                    XIII; properdin                                                      II and III                                                                               IgG; IgM; IgA; fibrinogen; beta-lipoprotein;                                   prothrombin; plasminogen; plasmin inhibitor;                                   factor V; factor VII; factor IX; factor X;                                     thrombin; antithrombin; isoagglutinins;                                        cerutoplasmin; complement C'1, C'3                                   IV-1      alpha.sub.1 -lipoprotein, cerutoplasmin;                                       plasmin inhibitor; factor IX; peptidase;                                       alpha-and-beta-globulins                                             ______________________________________                                    

    ______________________________________                                         Fraction  Proteins                                                             ______________________________________                                         IV-4      transferrin; thyroxine binding globulin;                                       serum esterase; alpha.sub.1 -lipoprotein; albumin;                             alkaline phosphatase                                                 V         albumin; alpha-globulin                                              VI        alpha.sub.1 -acid glycoprotein; albumin                              ______________________________________                                    

The above fractionation scheme can serve as a basis for further fractionations. Fraction II and III, for example, can be further fractionated to obtain immune serum globulin (ISG).

Another fractionation scheme involves use of frozen plasma which is thawed yielding a cryoprecipitate containing AHF (antihemophilic factor) and fibronectin and a cryosupernatant. The cryoprecipitate is then fractionated into fibronectin and AHF.

Polyethylene glycol has been used to prepare high purity AHF and non-aggregated ISG.

High risk products with respect to the transmission of hepatitis B and non-A, non-B are fibrinogen, AHF and prothrombin complex, and all other blood protein preparations except immune serum globulin and, because they are pasteurized, albumin solutions. Hepatitis tests presently available can indicate the presence of hepatitis B surface antigen, but there is presently no screening test for non-A, non-B hepatitis.

The present invention is directed to contacting with saturated or unsaturated fatty acid, a blood protein-containing composition such as whole mammalian blood, blood cells thereof, blood cell proteins, blood plasma thereof, precipitate from any fractionation of such plasma, supernatant from any fractionation of such plasma, cryoprecipitate, cryosupernatant or any portions or derivatives of the above that contain blood proteins such as, for example, prothrombin complex (factors II, VII, IX and X) and cryoprecipitate (factors I and VIII). The present invention is also concerned with contacting oleic acid, its esters or salts with a serum containing one or more blood proteins. Furthermore, the present invention is directed to contacting such oleic acid or oleic acid derivative with a blood protein-containing fraction containing at least one blood protein such as the following: factor II, factor VII, factor VIII, factor IX, factor X, fibrinogen and IgM.

Such blood protein-containing composition is contacted with oleic acid, its ester or salt. When an esterified form is employed, the ester group has an alkyl radical which contains, 1 to 4 carbon atoms, especially a methyl or ethyl group. Particularly, contemplated salts include the sodium and potassium salts, particularly sodium oleate.

The oleic acid, ester or salt can be used with or without the addition of wetting agents. It is possible, however, to use oleic acid, its ester or salt in conjunction with a wetting agent. Such wetting agent can be added either before, simultaneously with or after the oleic acid compounds contact the blood protein-containing composition. The function of the wetting agent is to enhance the contact of the virus in the blood protein-containing composition with the oleic acid compound. The wetting agent alone does not adequately inactivate the virus.

Preferred wetting agents are non-toxic detergents. Contemplated non-ionic detergents include those which disperse at the prevailing temperature at least 0.1% by weight of the fat in an aqueous solution containing the same when 1 gram detergent per 100 ml of solution is introduced therein. In particular there is contemplated detergents which include polyoxyethylene derivatives of fatty acids, partial esters of sorbitol anhydrides, for example, those products known commercially as "Tween 80", "Tween 20" and "polysorbate 80" and non-ionic oil soluble water detergents such as that sold commercially under the trademark "Triton X 100" (oxyethylated alkylphenol). Also contemplated are bile salts such as sodium deoxycholate as well as the "Zwittergents" which are synthetic zwitterionic detergents known as "sulfobetaines" such as N-dodecyl-N, N-dimethyl-2-ammonio-1 ethane sulphonate and its congeners or non-ionic detergents such as octyl-beta-D-glucopyranoside.

Substances which might enhance the effectiveness of oleic acid compounds include reducing agents such as mercaptoethanol, dithiothreitol, dithioerythritol, and dithiooctanoic acid. Suitable non-ionic surfactants are oxyethylated alkyl phenols, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene acids, polyoxyethylene alcohols, polyoxyethylene oils and polyoxyethylene oxypropylene fatty acids. Some specific examples are the following:

alkylphenoxypolyethoxy (3) ethanol

polyoxyethylene (2) sorbitan monolaurate

polyoxyethylene (20) sorbitan monopalmitate

polyoxyethylene (20) sorbitan monostearate

polyoxyethylene (20) sorbitan tristearate

polyoxyethylene (20) sorbitan monooleate

polyoxyethylene (20) sorbitan trioleate

polyoxyethylene (20) palmitate

polyoxyethylene (20) lauryl ether

polyoxyethylene (20) cetyl ether

polyoxyethylene (20) stearyl ether

polyoxyethylene (25) oleyl ether

polyoxyethylene (25) hydrogenated castor oil

polyoxyethylene (25) oxypropylene monostearate

The amount of wetting agent, if employed, is not crucial, for example, from about 0.001% to about 10%, preferably about 0.01 to 1.5%, can be used.

Di- and trialkylphosphates as described in copending application Ser. No. 514,375 now U.S. Pat. No. 4,540,573, issued Sept. 10, 1985 and Ser. No. 631,675 now pending may be used in conjunction with the oleic acid compounds which can also be used in conjunction with other inactivating agents such as alcohol or ethers with or without the copresence of wetting agents in accordance with copending application Serial No. 368,250 entitled "Sterilized Plasma and Plasma Derivatives and Process Therefor", assigned to the assignee hereof.

The ether or alcohol can be added in an amount of 1 to 50%, preferably 5 to 25% by weight, based on the volume of blood plasma, or concentrate or other blood plasma protein-containing composition to be treated.

Particularly contemplated ethers for inactivation use in accordance with the invention are those having the formula

    R.sup.1 --O--R.sup.2

wherein R¹ and R² are independently C₁ -C₁₈ alkyl or alkenyl which can contain an O or S atom in the chain, preferably C₁ to C₈ alkyl or alkenyl. Especially contemplated ethers are dimethyl ether, diethyl ether, ethyl propyl ether, methyl-butyl ether, methyl isopropyl ether and methyl isobutyl ether.

Alcohols contemplated include those of the formula

    R.sup.3 OH

wherein

R³ is a C₁ to C₁₈ alkyl or alkenyl radical which can contain one or more oxygen or sulfur atoms in the chain and which can be substituted by one or more hydroxyl groups.

Especially contemplated alcohols are those where the alkyl or alkenyl group is between 1 and 8 atoms. Particularly contemplated alcohols include methanol, ethanol, propanol, isopropanol, n-butanol, isobutanol, n-pentanol and the isopentanols. Also contemplated are compounds such as ethylene glycol, 1,2-propylene glycol, 1,3-propane diol, 1,4-butanediol, 2-hydroxy isobutanol (2-methyl, 1,2-dihydroxypropane).

Treatment of blood protein-containing compositions with trialkylphosphate is effected at a temperature between -5° C. and 70°, preferably between 0° C. and 60° C. The time of such treatment (contact) is for at least 1 minute, preferably at least 1 hour and generally 4 to 24 hours. The treatment is normally effective at atmospheric pressure, although subatmospheric and superatmospheric pressures can also be employed.

Normally, after the treatment, the oleic acid compound and other inactivating agents, for example, ether, are removed, although such is not necessary in all instances depending upon the nature of the virus inactivating agents and the intended further processing of the blood plasma protein-containing composition.

To remove ether from plasma, the plasma is generally subjected to a temperature of 4° C. to 37 ° C. with a slight vacuum imposed to draw off residual ether. Preferably means are provided to spread the plasma as a thin Other methods for removal of ether in activating agents include:

(1) bubbling of nitrogen gas;

(2) diafiltration using ether insoluble, e.g. "TEFLON", microporous membranes which retain the plasma proteins;

(3) absorption of desired plasma components on chromatographic or affinity chromographic supports;

(4) precipitation, for example, by salting out of plasma proteins;

(5) lyophilization, etc.

When alcohol or non-ionic detergents are employed with the oleic acid compounds they are removed by (2) to (5) above.

Di- or trialkylphosphate can be removed as follows:

(a) Removal from AHF can be effected by precipitation of AHF with 2.2 molal glycine and 2.0 M sodium chloride

(b) Removal from fibronectin can be effected by binding the fibronectin on a column of insolubilized gelatin and washing the bound fibronectin free of reagent.

Alcohol is normally removed together with detergent. If the detergent includes both alcohol and ether, the ether is normally removed before the alcohol.

The process of the invention can be combined with still other modes of inactivating viruses including those for non-lipid coated viruses. For instance, a heating step can be effected in the presence of a protein stabilizer, e.g., an agent which stabilizes the labile protein (AHF) against inactivation by heat. Moreover, the heating can be carried out using stabilizers which also tend to protect all protein, including components of the virus, against heat if the heating is carried out for a sufficient length of time, e.g., at least 5 hours and preferably at least 10 hours at a temperature of 50°-95° C., especially 60°14 70° C. By such mode, the virus is preferentially inactivated, nevertheless, while the protein retains a substantial amount, e.g., greater than or equal to 80% of its protein activity. Of course, the best treatment can also be carried out simultaneously with the oleic acid treatment.

The treatment of plasma or its concentrates, fractions or derivatives in accordance with the present invention can be effected using oleic acid, its ester or salt immobilized on a solid substrate. The same can be fixed to a macro-molecular structure such as one of the type used as a backbone for ion exchange reactions, thereby permitting easy removal of the oleic acid compounds from the plasma or plasma concentrate. Alternatively, the oleic acid compounds can be insolubilized and immobilized on a solid support such as glass beads, etc., using silane or siloxane coupling agents.

The method of the present invention permits the pooling of human blood plasma and the treatment of the pooled human blood plasma in the form of such pooled plasma. It also permits the realization of blood product derivatives such as factor VIII, gamma globulin, factor IX or the prothrombin complex (factors II, VII, IX, X), fibrinogen and any other blood derivative including HBsAg used for the preparation of HBV vaccine, all of which contain little or no residual infective hepatitis or other viruses.

The oleic acid, its ester or salt is preferably employed in a concentration of a least 0.02 weight percent, generally 0.025-0.1 weight percent. Concentrations higher than 0.04 weight percent do not appear to provide improved virus inactivation as at the lower concentrations of 0.02-0.04, especially about 0.035 the degree of viral inactivity is such that virus is undetectable or substantially undetectable.

The oleic acid treatment is effected for up to about 5 hours as longer periods of treatment, e.g., 6 hours decrease the yield of labile protein, at least in the case of AHF when concentrations of sodium oleate of 0.1 weight percent are employed.

At oleic acid concentrations of 0.01-0.06 weight percent at contact times of up to about 5 hours, very acceptable AHF yields are found. For instance, at a contact time of 1 hour using sodium oleate at an oleic acid concentration of 0.02-0.06, AHF yield in excess of 60% are obtained. When the concentration is 0.02-0.035 the AHF yield is in excess of 70%. Using a contact time of 4 hours, one observes a greater degree of AHF yield loss. Thus, at such higher contact times, the oleic acid concentration should be below about 0.038 and generally 0.020-0.038 weight percent.

The inactivation can be carried out at 0°-60° C., although it is preferred at 20°-30° C.

BRIEF DESCRIPTION OF DRAWING

The annexed drawing consists of two graphs each containing two curves. One graph plots oleic acid concentration against viral infectivity which the other plots the same concentration against AHF yield. The oleic acid used for the experiments, of the figure, was employed in the form of its sodium salt. AHF was used as a model blood plasma because it is considered to be the most labile blood protein. VSV was chosen as a model virus as its behavior predicts the behavior of lipid-enveloped viruses such as hepatitis B virus and for the additional reason that chimpanzee test animals are required to determine elimination of hepatitis virus.

COMPARATIVE EXAMPLES

In the table below there is set forth results obtained using other viral inactivation agents and oleic acid (as the sodium salt). The conditions under which the oleic acid salt were employed are not the preferred conditions. Hence, while exceptional VSV inactivation was achieved, the AHF yield was also effected, sometimes quite significantly.

                                      TABLE                                        __________________________________________________________________________     EFFECT OF FATTY ACIDS ON AHF AND VSV                                                                            AHF VSV                                       Reference                        Yield                                                                              Decline                                   Agent  Reference                                                                            Conditions Reported                                                                      Conditions Used                                                                          (%) (log)                                     __________________________________________________________________________     BHT    1     Up to 0.011%,                                                                            0.1%, 6 hrs, amb T                                                                       100 0.4                                                    30 min, amb T                                                     Linoleic Acid                                                                         2     0.001-0.01%                                                                              0.01%, 6 hrs, amb T                                                                      97  0.4                                       Na Salt      10-60 min, 25° C.                                          Linolenyl                                                                             3     0.00012%, 20 min,                                                                        0.01%, 6 hrs, amb T                                                                      93  0.1                                       alcohol      25° C.                                                     Oleic Acid                                                                            2,4   0.001-0.01%, 10-60                                                                       0.1%, 1 hr. amb T                                                                        44  >4.2                                      Na Salt      min, 25° C.                                                                       0.1%, 6 hrs, amb T                                                                        1  >4.2                                      __________________________________________________________________________      1 Keith, A. D. and Sniper, W., "Inactivation of lipid containing viruses       with butylated hydroxytoluene", U.S. Pat. No. 4,350,707, 1982.                 2 Kohn, A., Gitelman, J., and Inbar, M., "Unsaturated free fatty acids         inactivate animal enveloped viruses", Arch. Virology, 66:301 (1980).           3 Sands, J., Auperin, D., and Snipes, W., "Extreme sensitivity of              enveloped viruses, including herpes simplex, to longchain unsaturated          monoglycerides and alcohols", Antimicrobial Agents and Chemother., 15:67       (1979).                                                                        4 Stock, C. Cl, and Francis, T. Jr., "The inactivation of the virus of         epidemic influenza by soaps, J. Exp. Med., 71:661 (1940).                

The present invention is directed, inter alia, to producing a blood plasma protein-containing composition such as blood, blood plasma blood plasma fractions, etc., which is substantially free of infectious virus, yet which contains a substantial amount of viable (undenatured) protein. More particularly, the present invention is directed to inactivation of lipid-containing virus and preferentially inactivation of hepatitis B and non-B, non-A virus. Other viruses inactivated by the present invention include, for example, cytomegaloviruses, Epstein Barr viruses, lactic dehydrogenase viruses, herpes group viruses, rhabdoviruses, leukoviruses, myxoviruses, alphaviruses, Arboviruses (group B), paramyxoviruses, arenaviruses, coronaviruses, and retroviruses.

According to the present invention, there is contemplated a protein-containing composition - a product produced from normal or cancerous cells or by normal or cancerous cells (e.g., via recombinant DNA technology), such as mammalian blood, blood plasma, blood plasma fractions, precipitates from blood fractionation and supernatants from blood fractionation having an extent of inactivation of virus greater than 4 logs of virus such as hepatitis B and non-A, non-B, and having a yield of protein activity to total protein of at least 70%, preferably at least 95% and most preferably 98% to 100%.

Further contemplated by the present invention is a composition containing factor VIII which is substantially free of hepatitis virus to the extent of having an inactivation of greater than 4 logs of the virus and a yield of protein activity to total protein of at least 70%, preferably at least 85%, more preferably at least 95% and most preferably 98% to 100%.

The process of the present invention has been described in terms of treatment of plasma, plasma fractions, plasma concentrates or components thereof. The process, however, is also useful in treating the solid components of blood, lysates or proteins secreted by cells. Thus, also contemplated are treatment of platelet concentrates, white cell (leukocyte) concentrates, and leukocyte-poor packed red cells as well as platelet rich plasma, platelet concentrates and platelet poor plasma including packed cell masses comprising the white buffy coat consisting of white blood cells above packed red cells. Also contemplated is the treatment of masses containing concentrates of granulocytes, monocytes, interferon, and transfer factor.

One can treat plasma itself according to the present invention or fresh frozen plasma, thawed frozen plasma, cryoprecipitate, cryosupernatants or concentrates from frozen plasma as well as dilution products thereof.

By the same manipulative steps discussed above, virus present in products of normal or cancerous cells can be inactivated while retaining labile protein activity in such products. For instance, by the same oleic acid, ester or salt treatment one can inactivate products produced using normal or cancer cells, the exudate from normal or cancerous cells, hybridomas and products produced by gene splicing. Such treatment does not substantially adversely affect the desired protein. Cells used for production of desired protein can, of course, be mammalian as well as non-mammalian cells. 

What is claimed is:
 1. A process for rendering a blood product which comprises a labile protein substantially free of lipid-containing viruses without incurring substantial protein denaturation comprising contacting said product with an effective amount of C₁ -C₄ -alkyl oleic acid, its ester or alkali or alkaline earth metal salt thereof for a sufficient period of time to inactivate virus contained therein.
 2. A process according to claim 1 wherein an oleic acid salt is employed.
 3. A process according to claim 2 wherein said salt in sodium oleate.
 4. A process according to claim 1 wherein oleic acid is employed.
 5. A process according to claim 1 wherein said contacting is conducted in the presence of a wetting agent.
 6. A process according to claim 5 wherein said wetting agent is a non-ionic detergent.
 7. A process according to claim 5 wherein said wetting agent is added to said protein-containing composition prior to contacting said protein-containing composition with said oleic acid, ester or salt.
 8. A process according to claim 5 wherein said wetting agent is added simultaneously with said oleic acid, ester or salt to said protein-containing composition.
 9. A process according to claim 5 wherein said wetting agent is added after said oleic acid, ester or salt contacts said protein-containing composition.
 10. A process according to claim 6 wherein said detergent is a partial ester of sorbitol anhydrides.
 11. A process according to claim 1 further comprising conducting said contacting in the presence of an inactivating agent selected from the group consisting of ethers and alcohols.
 12. A process according to claim 5 further comprising conducting said contacting in the presence of an inactivation agent selected from the group consisting of ethers and alcohols.
 13. A process according to claim 1 wherein said product is a blood product selected from the group consisting of whole blood, blood plasma, a plasma concentrate, a precipitate from any fractionation of such plasma, a supernatant from any fractionation of said plasma, a serum, a cryoprecipitate, a cell lysate, and proteins induced in blood cells.
 14. A process according to claim 1 wherein said product contains one or more proteins selected from the group consisting of fibrinogen, factor II, factor VII, factor VIII, factor IX, factor X, factor I, immunoglobins, prealbumin, retinol-binding protein, albumin, alpha-globulins, beta-globulins, gamma-globulins, factor III and the complement components, fibronectin, antithrombin III, hemoglobin, interferon, T-cell growth factor, plasminogen activator.
 15. A process according to claim 1 wherein said protein-containing composition is the product of a non-blood normal or cancerous cell or the product of gene splicing.
 16. A process according to claim 1 wherein said period of time is between about 1 and 5 hours.
 17. A process according to claim 1 wherein said contacting is conducted at a temperature of between about 0° C. and about 60° C.
 18. A process according to claim 1 wherein said oleic acid, ester or salt is employed in a concentration of between about 0.02 weight percent and about 0.1 weight percent.
 19. A process according to claim 18 wherein said oleic acid, ester or salt is employed in a concentration of between 0.02 weight percent and 0.04 weight percent for 1-4 hours at room temperature.
 20. A process according to claim 18 wherein said product comprises factor VIII.
 21. A process according to claim 18 wherein said product comprises factor IX.
 22. A process according to claim 1, wherein said product has an extent of inactivation of virus of greater than 4 logs of virus and has a yield of protein activity to total protein of at least 70%.
 23. A process according to claim 22, wherein the yield of protein activity to total protein is at least 95%.
 24. A process according to claim 22, wherein the yield of protein activity to total protein is 98% to 100%. 